Pulling Load Research Articles

Экспериментальные исследования комбинированных анкеров и варианты их практического применения

In the article, the authors for the first time proposed combined anchor structures that can work effectively as wire anchors working on a pulling load, as well as pile anchors working on a pressing force. Such structures can be effectively used as anti-landslide structures, support and anchor foundations, which are also patented by the authors and their designs are given in the article. In practice, such structures are necessary as foundations, for poles of power lines, high towers exposed to high wind loads and other structures. The support can work both on a pressing load and on pulling out, depending on the specific conditions. The research methodology is described and the results of experimental studies are presented. During the research, the following factors were taken as the main factors: the diameter of the pile and the conical tip, the length of the pile part of the combined anchor, the distance from the end of the pile to the conical tip. The pulling force was adopted as an optimization parameter.

Experimental and numerical investigation of tensile-loaded staggered bolted and hybrid pultruded composite double lap joints

On-site construction projects typically employ staggered fastener patterns. This article describes the application of Hollo Bolts (HB). It also highlights the effectiveness of using flexible epoxy adhesive to increase the load-carrying capacity of staggered connections fastened with HB. The distribution of loads between connecting elements largely determines joint performance. Pultruded glass fiber reinforced polymer (PGFRP), bolted (B), and hybrid bolted/bonded (BB) double lap joints were subjected to a typical pulling load and numerically validated in this investigation. To simulate delamination effects, a Cohesive Zone Model with a 3D progressive damage analysis was developed. In addition, a parametric study capturing the influence of various geometrical variables such as e/d, overlap length, bolt size, adherend thickness, and the number of bolts was used to compare both categories of joints in detail. The results indicate that for staggered connections fastened with HB, an efficient load transfer can be obtained in conjunction with flexible epoxy adhesive. It is anticipated that this interaction will be even more effective as the overlap length, adherend thickness, and fastener diameter increase. The present study proves that BB connections are 43.56% stronger than B connections.

Experimental Study on Bonding Performance between Prestressed Concrete Pipe Piles and Core Grout

To make the bearing capacity tests safer and more affordable for prestressed high-strength concrete (PHC) piles, this paper proposes a reaction device for anchor piles filled with core grout based on the geometric and mechanical characteristics of PHC piles. The proposed reaction device has the advantages of convenient construction, strong controllability of the connection quality and low cost. In addition, the pile will not experience prestress unloading or tensile stress under the effect of the upward pulling load. To promote the application of the reaction device developed for PHC pile bearing capacity tests, experimental studies are conducted on the bonding performance between the core grout and the inner wall of the PHC pile. The influence of various factors such as the strength of the core grout, the grouting length, the curing time, and the inner diameter of the PHC pile on the bond strength between the core grout and the inner wall of the PHC pile are investigated. Results show that as the inner diameter of the PHC pile increases, the bond strength between the core grout and the inner wall of the PHC pile decreases with a maximum difference of 5%. The bond strength decreases as the grouting length increases, and gradually stabilizes, with a difference of no more than 10% between the maximum and minimum bond strength values. The higher the strength of the grout is, the greater the bond strength between the core grout and the inner wall of the PHC pile is. The bond strength between the core grout and the inner wall of the PHC pile increases with the increase of the curing time within 28 days of curing, and the bond strength at 3 days meets the requirements of the PHC pile bearing capacity test.

Cyclic shear fatigue of orthodontic brackets bonded to enamel using self-adhering flowable composites

BackgroundSelf-adhering composites are claimed to bond to teeth without prior acid etching and bonding steps. This study aimed to evaluate the cyclic shear fatigue (CSF) of metal orthodontic brackets bonded to enamel using self-adhering flowable composites (Constic and VertiseTM Flow) in comparison with that of total-etch and self-etch adhesives. Materials and methodsTwenty-five human premolars comprising 100 surfaces were randomly divided into four groups (n = 25): total-etch, self-etch, Constic, and VertiseTM Flow. A total of 10 surfaces were used per group for baseline static shear bond strength (SSBS) evaluation and 15 surfaces for CSF evaluation. Each tooth was treated with the four bonding agents. Both SSBS and CSF were evaluated using a universal testing machine. For CSF, the staircase method was used with an initial pulling load equivalent to 60% of the SSBS of each group for 1000 cycles or until failure. The adhesive remaining index (ARI) was evaluated for surviving samples using a stereomicroscope. Statistical analysisA one-way ANOVA with Tukey’s post hoc test was used to analyze the CSF data, and a chi-square test was used to analyze the ARI. ResultsThe total-etch adhesive showed significantly higher CSF values than that of the other groups (p < 0.001). Both total-etch (10.78 ± 0.31 MPa) and self-etch (6.75 ± 0.91 MPa) adhesives showed significantly higher CSF than did Constic (1.94 ± 0.31 MPa) and VertiseTM Flow (2.01 ± 0.25 MPa), (p < 0.001). The ARI indicated that more resin remnants were observed with the total-etch and self-etch adhesives than those with the self-adhering flowable composites. However, no significant differences were observed among groups (p > 0.05). ConclusionsTotal-etch and self-etch adhesives showed satisfactory bond strengths for orthodontic treatment. However, Constic and VertiseTM Flow self-adhering flowable composites may not be clinically sufficient for bonding metallic orthodontic brackets to enamel.

Micromechanical analysis of suction pile-granular soil interaction under inclined pulling load of mooring line: Mooring depth effect

The micro-mechanism of mooing depth effect on the interactions between suction piles and granular soil remains unclear. This study investigates suction pile-soil interaction behaviour under the inclined pulling load of a mooring line, as well as mooring depth effects. The discrete element method (DEM) was used to model granular soil, while the suction pile was modelled via finite element method (FEM). Results in DEM-FEM simulations were compared with that in the model tests first. Then, the macro and micro behaviours during suction pile-soil interactions were analysed. Based on the results, the pulling force-displacement curves could be categorised into two groups according to the curve shapes associated with suction pile motion patterns. Discontinuity and occurrences of large soil deformation were successfully reproduced. Next, suction pile movement and deformation were quantitatively analysed in terms of vertical pull-out displacement, pile rotation, and effective support around suction piles. Furthermore, the particle-scale behaviours of soil were analysed, finishing with the identification of conclusive mechanical failure patterns. This study indicates that neglecting the mooring depth of the mooring lines may lead to a significant underestimation of the uplift capacity of a suction pile, as well as misinterpretation of the failure mode of the granular soil.

Effect of Multiwall Carbon Nanotubes on Tensile Strength of Cross Lap Joint

Abstract: This paper compares the tensile strength of an adhesively bonded single cross lap joint with and without the addition of multiwall carbon nanotubes (MWCNT) in the adhesive. Tensile strength analysis of adhesively bonded cross lap joint is done by applying pulling load which produces tensile stress at overlap between two substrates which joined together by using adhesive. Cross lap joint were created using Al-Al substrates. Five tests were performed on Al-Al substrates with and without the addition of MWCNT in the adhesive for each specimen. MWCNT filler particles increase the toughness and strength of epoxy resin when compared to epoxy resin that does not contain MWCNT. MWCNT fill epoxy resin increases toughness and resists crack formation, increasing the interface strength between two substrates.

Micromechanical analysis of suction pile-granular soil interaction under inclined pulling load: Effect of pulling angle

The micro-mechanism of interaction between the suction pile and granular soil under the inclined pulling load of mooring lines remains unclear. This study investigated suction pile-soil interaction behaviour under an inclined load with different pulling angles using the coupled DEM-FEM. Discontinuity and large deformation occurrences in soil, such as voids, gaps, soil upheaval and collapse, were successfully modelled. The changes in pulling force under different pulling angles were found to stem from the suction pile-soil interaction modes. Additionally, the rotation axes of a suction pile were obtained by examining soil pressure distributions on anchor sides, and the resulting rotation angles of the suction pile were compared with each other based on these axes. The discussion includes a schematic diagram that explains the development of the rotation axes and an analysis of the shear intensity on the anchor surface. Further analysis of a series of typical particle-scale behaviours is presented, finishing with the identification of conclusive mechanical patterns of soil failure. The study suggests that neglecting the pulling angle of mooring lines can result in severely misestimating the pull-out capacity of a suction pile and misjudging the failure pattern of granular soil.

THE RESULTS OF LABORATORY STUDIES OF THE OPERATION OF MODELS OF PYRAMIDAL-PRISMATIC PILES ON THE EFFECT OF VERTICAL PULLING LOAD IN CLAY SOIL

This paper presents the results of laboratory tests of models of pyramidal-prismatic piles on the effect of vertical pulling load. The experiments were carried out in clay soil. It is established that models of pyramidal-prismatic piles, depending on the size of the pyramidal section, can have both greater and lesser resistance compared to prismatic and pyramidal (control) piles. Thus, it was found that the resistance of pyramidal-prismatic piles to the pulling load is 1.19-1.80 times higher than the resistance of a model of a prismatic pile with a cross-section size of 20×20 mm. Compared with the model of a prismatic pile with a cross-section size of 30 ×30 mm and with the model of a pyramidal pile (with a cross-section size of 30×30 mm at the top and 20×20 mm at the bottom), the models of pyramidal-prismatic piles have less resistance (by 6-45%). An increase in the size of the upper section of the pyramidal part of the PPP has a more significant effect on increasing their resistance to pulling out than an increase in the length of their pyramidal section. Correlations have been established that can be used for a preliminary assessment of the resistance of pyramidal-prismatic piles to the pulling load relative to the resistance of traditional (prismatic and pyramidal) piles.

A phase field approach to fracture for hyperelastic and visco-hyperelastic materials applied to pre-stressed cylindrical structures

In this investigation, the mechanical modeling of nonlinear visco-hyperelastic residually stressed materials obtained from an invariant-based constitutive energy framework is coupled with the phase field approach to fracture. The main target regards the extension of the phase field method to simulate pre-stressed cylindrical structures subjected to monotonic axial pulling load upon failure. This formulation is incorporated into a numerical procedure using the Finite Element Method (FEM), in particular, it is implemented in the commercial FE package ABAQUS as a user subroutine UMAT. Results suggest the dependence of the mechanical behavior and the crack pattern of these structures on not only viscous parameters like the relaxation time and the displacement rate, but also on the strength of the residual stress field, which in turn depends on geometrical characteristics of the cylindrical structure such as the radius or the length. A range of solutions related to crack propagation is shown for different cylindrical structures, from azimuthal crack propagation to axial one. The proposed framework aims to provide an extended application for the already-defined visco-hyperelastic formulation by the inclusion of residual stresses.

Structural analysis of cotton stalk Puller and Shredder Machine

World scenario after pandemic COVID-19 has been drastically changing and researchers more focusing on, to minimize the post-pandemic effects on economy, energy sustainability and food security. Agriculture sector is playing pivotal role in world food security and energy sustainability. There is high need to optimize the mechanization technologies to increase the yield in limited energy inputs and operation time to fulfill the world growing food demand. This research is mainly focused on the design development and structural analysis aiding with Finite Element Analysis (FEA) approach for Cotton Stalk Puller and Shredder machine (CSPS) to cut the crop leftovers, soil conditioning (shredding the plant waste into soil) and sowing of next crop in single run by conserving input resources. The experimental trials revealed that there is high pressure on cutting blades, chocking of shredder section and excessive pulling load on tractor hitches, which affected the machine’s performance. To mitigate deficiencies and design optimization to improve the machine safety/reliability, the structure analysis carried out. Six core components of machine including baseplate, blade, gear system, root digger, pulley and shaft has investigated as per field conditions. The results revealed that the material of blade, root digger and teeth of gear system receiving the high stress under the operational conditions which results the edge wear and damage. The carbonization up to one-millimeter thickness can provide the extra strength to bear the excessive load on edge layers.

Loosening and fracture behavior of hybrid titanium-to-steel threaded connection under cyclic loading condition

Hybrid threaded connection involving titanium alloy and conventional steel components is introduced and studied in the face of lightweight metals application trend in modern machinery design. Pre-tightening procedure and loosening test were conducted based on specially designed specimen regarding cyclic pulling load condition. The loosening and fracture behavior were intentionally investigated through both mechanical analysis and related microstructure observation. The loosening evolution tendency along with the corresponding low cycle fatigue process was obtained, which was then further related with the examined structural mechanical responses and thread wear mechanism. Results have shown that in the early stage of fatigue process the pretension would experience a rapid and mass reduction accompanied with a high rate cyclic hardening response of structure. The cyclic load induced thread wear occurred mainly in the titanium nut component, which involved abrasive wear, fatigue wear and oxidative wear mechanism. Besides, the thread root turn closest to the bearing surface was demonstrated as major position of stress concentration and strain accumulation, making it critical source for loosening initiation and fatigue fracture, which should be properly optimized in both designing and fabricating process.

Behavior of Pre-Stressed Arch Subjected to Sliding Load

This paper investigates the behavior of a pre-stressed arch under a sliding load, where the initial configuration can be obtained from the buckling of a straight column. The shape of the pre-stressed arch can be varied by increasing the end shortening. Subsequently, a sliding load is applied at a certain height level. The orientation of the applied load maintains the right angle with respect to the tangential line of the arch. By moving the load horizontally, the behavior of the arch can be explored. The governing differential equations of the problem can be obtained by equilibrium equations, constitutive relation, and nonlinear geometric expressions. The exact closed-form solutions can be derived in terms of elliptic integrals of the first and second kinds. In this problem, the arch can be divided into two segments where each segment is a part of a buckled hinged-hinged column mounted on an inclined support. The shooting method is employed to solve the numerical solutions for comparing with the elliptic integral method. The stability of the pre-stressed arch is evaluated from vibration analysis, where the shooting method is again utilized for solving the natural frequencies in terms of a square function. A simple experiment is set up to explore the equilibrium shapes. Poly-carbonate sheet is utilized as the pre-stressed arch. From the results, it is found that the results obtained from elliptic integral method are in excellent agreement with those obtained from shooting method. The equilibrium shapes from the theoretical results can also compare with those from the experiment. The pre-stressed arch can lose its stability and snap into an upside-down (inverted) configuration depending on the ratio of rise to span-length and loading height. The instability of the arch is not only detected during the pushing of the sliding load but a pulling load can also cause unstable behavior of the arch.

Broaches for cylindrical and slotted holes

Broaches are developed for machining of holes, the use of which reduces pulling forces, vibrations and load on the tool teeth, which increases tool life, quality and productivity of machining, and reduces its cost. Keywords: broach, durability, quality, effectiveness, productivity. asylbek_kasenov@mail.ru, a.kairatolla@mail.ru, asylkhan_m@mail.ru, aya_taskarina@mail.ru

Differential activation of the plantar flexor muscles in balance control across different feet orientations on the ground

The ankle plantar flexor muscles act synergistically to control quiet and dynamic body balance. Previous research has shown that the medial (MG) and lateral (LG) gastrocnemii, and soleus (SOL) are differentially activated as a function of motor task requirements. In the present investigation, we evaluated modulation of the plantar flexors' activation from feet orientation on the ground in an upright stance and the ensuing reactive response to a perturbation. A single group of young participants (n = 24) was evaluated in a task requiring initial stabilization of body balance against a backward pulling load (5% or 10% of body weight) attached to their trunk, and then the balance was suddenly perturbed, releasing the load. Four feet orientations were compared: parallel (0°), outward orientation at 15° and 30°, and the preferred orientation (M = 10.5°). Results revealed a higher activation magnitude of SOL compared to MG-LG when sustaining quiet balance against the 10% load. In the generation of reactive responses, MG was characterized by earlier, steeper, and proportionally higher activation than LG-SOL. Feet orientation at 30° led to higher muscular activation than the other orientations, while the activation relationship across muscles was unaffected by feet orientation. Our results support the conclusion of task-specific differential modulation of the plantar flexor muscles for balance control.

Rig Load Prediction Model in Horizontal Directional Drilling within Water-Rich Unstable Strata

In horizontal directional drilling (HDD) construction, the rig pulling load is the load directly applied to the rig, which is an important basis for selecting power and checking capability of drilling equipment. Existing models cannot directly calculate the rig pulling load during the pull-back process. In this study, a model that takes into account the influence of the drill string and the soil pressure was developed to predict rig pulling load. The accuracy of the model is verified by comparison with existing models and field tests. The results show that pullback capability of rig should be determined by the maximum rig load instead of the maximum pull head load. For lighter high-density polyethylene (HDPE) pipes, using the mud with good lubrication function is the most effective to reduce the maximum rig load, however, for heavier steel pipes, the most effective way to reduce the maximum rig load is choosing pipe delivery method with less resistance. The field test proves that the model can predict the rig load accurately when installing pipes in water-rich unstable strata.

Bearing capacity of bored piles made with polymer drilling mud

The main results of the work on the analysis of the possibility of using polyacrylamide drilling muds for the installation of drill piles, barrettes and slurry walls in sandy soils are presented. The results of the study of the possibility of solutions to keep the walls of boreholes from collapse, laboratory studies of the effect of polyacrylamide solutions on the shear strength of soils, as well as the results of field tests of piles with static pulling load are reflected.

Effect of Moisture Content on the Angle of Repose and Coefficient of Kinetic Friction of Sago Trunk (Metroxylon spp.)

Starch is one of the food sources that can be extracted from cereals, roots, tubers and stem. Sago palm (metroxylon spp.) is one example of the starch source. The efficiency of the starch extraction process depends on the mechanical properties of process material. This study was conducted to determine the angle of repose between grated sago and kinetic friction of the contact surface between process material and machine. The angle of repose (θ) of grated sago was determined by using a cone shape hopper attached to an adjustable height bar. The cone was filled with a 100g sample of grated sago and slowly adjusted to an upward direction to release the grated sago and will form a conical shape. The cone shape base diameter and height were measured. Next, a square block of debarked sago trunk (8cm × 8cm × 8cm) was placed on a stainless steel plate and attached to a rope at middle connected to force gauges. The pulling speed was at 1.27 mm/min and the result of total pulling load (F) was recorded. The process was repeated for materials with different moisture content (MC) of 60%, 50%, 40%, and 30%. Based on the experimental results, the angle of repose (AoR= 47.000±0.31) and coefficient of kinetic friction (μ k) 0.88±0.005 at MC= 60% showed decrease in value (AoR= 43.610±0.34; μ k = 0.83±0.002) when the MC decrease by 30% (P&lt;0.01).

Cопротивляемость моделей пирамидально-призматических свай статической выдергивающей нагрузке

The article presents results of testing models of piles with different longitudinal shapes under the action of a static pulling load, performed in laboratory conditions. The article reveals resistance of the pyramidal-prismatic piles can be either more or less than the resistance of the prismatic and pyramidal piles. It was found that an increase in the length of the pyramidal part of the pile, as well as the size of its cross-section at the top, affect the resistance of the pile to pull-out load. So, the resistance of these piles is 1.28-1.85 times higher than the resistance of a prismatic pile with a section size of 20×20 cm, and 8-36% lower than the resistance of a prismatic pile with a section size of 30×30 cm and a pyramidal pile (with a top section size of 30×30 cm and at the bottom - 20×20 cm). Correlation dependencies are obtained to assess the stability of pyramidal-prismatic piles in relation to the bearing capacity of piles with traditional longitudinal section shape (prismatic and pyramidal piles).

Backward Sled Pulling Load–Velocity Relationship in Youth: A Backward–Forward Comparison

To establish the load–velocity relationships during backward sled pulling and compare this to forward sled pulling and determine the reliability of running speeds and associated load–velocity regression slopes in youth athletes. Twenty-one boys (age, 13.6 ± 0.28 years old; height, 1.72 ± 0.09 m; mass, 66.1 ± 8.2 kg; maturity, 0.57 ± 0.72 years from peak height velocity) performed backward and forward resisted running on three occasions. Load–velocity relationships were established using an un-resisted sprint and resisted sled pull with loads of 25%–81% body mass (BM) in both directions, and the reliability of sprint times at each load and the load–velocity regression slopes were examined. The load–velocity data was reliable across multiple testing occasions for backward (CV ≤ 7.2%; ICC 0.67–0.91) and forward sled pulling (CV ≤ 7.2%; ICC 0.66–0.91). From the regression lines (R2 ≥ 0.99; P ≤ 0.01), it was observed that averaged loads across the sample of 31%, 46% and 61% BM resulted in 27%, 38% and 48% decrease in velocity during backward sled pulling and 23%, 33% and 43% during forward sled pulling. Increasing backward and forward loads by ∼ 13% and ~ 15% BM respectively, reliably resulted in ∼ 10% decreases in velocity. If contractile overload of the lower limbs is a focus of training then practitioners should preferentially use backward sled pulling. Both backward and forward sled pulling can be used in a similar manner regarding loading, though backward velocity is more sensitive to load and therefore overloading backward motion should be prescribed with this in mind.

Enhancement of Fatigue Strength on SAE 1541 Steel Link Plate with Slip Ball Burnishing Technique

This research paper describes a technique for the enhancement of the fatigue strength of the chain link plate in the drive system of a military armoured vehicle. SAE 1541 steel link plates of chains were subjected to cyclical tensile stress due to repeated loading and un-loading conditions. The crack was getting originated from the pitch hole and growth perpendicular to the chain pulling load, due to fatigue mechanism. In general plate holes are manufactured using the conventional process. An additional novel technique called the slip ball burnishing (SBB) method is applied for improving the hole properties. The improvement is made by producing local plastic deformation, improving surface finish and compressive residual stress throughout in the pierced hole. Both the conventional process (CP) and the SBB technique have been evaluated by optical, profile, surface roughness and micro harness tests. Experimental fatigue test validations were done in both chain samples using the Johnson-Goodman method. SBB chains passed 3x106 cycles at the load of 17.61 kN and CP chains passed 3x106 cycles at the load of 13.92 kN. The conclusion was that SBB made a significant improvement of 26.51 per cent of fatigue strength compared to CP.